Japanese Patent Application Laid-Open Publication No. 2011-96, 506 discloses such a large area light source, on which a positive film indicating a time table in the station, a guide in an open space at the front of the building or on the building wall, an advertisement and so on is arranged, and which is formed about 1 meter long by 2 meters wide, whereby a plurality of LED bars divided in its longitudinal direction is arranged in series in a heat dissipation base, and an incident light is guided into an incident light edge of its light guide plate. The arrangement of the LED bars in series in a heat dissipation base is made by integrally forming a holder of the LED bar in cross-sectional L-shape using extruded aluminum, including a light source holder C-shaped in cross section that opens toward incident light edge of the light guide plate, and an upstand that is made as a seat for the heat dissipation plate and a support plate back the light guide plate on the back of the light source holder to dissipate heat from the holder of the LED bars. The area light source is integrated by threading screw either from the light source holder into the light guide plate via an unloaded hole through the support circuit board, or from a flame arranged outside into the light guide plate via a lace hole of the light holder and the unloaded hole of the support circuit board. This configuration makes it possible to absorb heat shrink of the light guide plate that is subjective to direct daylight. The LED bars are arranged in series in the heat dissipation base by inserting the LED bars into a C-shaped slit of the light source holder and infilling such a spacer between the circuit board of the LED bars and the opposite projection positioned at the incident light edge of the light source holder, and the LED bars are electrically connected to each other either using a connector or soldering lead wire, generally, soldering electrodes of ends of the adjacent LED bars in series.